Blue Whales Roam Dangerously Close to Shipping Lanes

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The feeding grounds of blue whales along the U.S. West Coast
overlap dangerously with shipping lanes, placing the behemoths in
danger of collisions with ships, researchers say.

This finding could help prevent human threats to these endangered
titans, scientists added.

Blue whales are the largest animals that have ever lived on
Earth, weighing in at 330,000 lbs. (150,000 kilograms) and
reaching up to 108 feet (33 meters) long. They are gentle giants,
grazing the oceans for tiny bits of food in seawater, with mouths
large enough to hold 100 people.

Blue whales, along with many other whales, became endangered due
to commercial whaling. Their numbers have been slow to grow,
despite rules protecting them established by the International
Whaling Commission in 1966, and scientists have suggested that
one reason for this slow recovery may be collisions with ships
that injure, or even kill, the whales. [ See
Photos of Blue Whales & Shipping Lanes ]

For instance, in 2008, five dead blue whales were discovered in
the Pacific Ocean in a seven-week period, and three of them were
confirmed to have been hit by ships. "That made everyone step
back and say, 'Whoa, this may potentially be a big problem,'"
said lead study author Ladd Irvine, a marine mammal ecologist at
Oregon State University.

Tagging blue whales

To learn more about where blue whales roam in order to better
protect them, scientists tracked them using tags equipped with
satellite transmitters. They attached tags onto 171 blue whales
off the coast of California from 1993 to 2008, for the most
comprehensive study of blue whale movements ever conducted.

"First, you have to find the whales," Irvine said. "These whales
are huge, but the ocean is even bigger. A lot of days, you can
just go out on a boat for days and not find anything. And since
we use small boats, we can't operate in very bad weather —
anything more than a 20 mph (32 km/h) wind — since we can't
balance well in the boats to put tags on [the whales] when the
water gets choppy. And to attach the tags, we have to get about 6
to 8 feet (1.8 to 2.4 m) away from them, and whales spend 95
percent of their time underwater, so we have to wait for them to
surface first." [ In
Photos: Tracking Humpback Whales ]

The scientists analyzed the
paths of blue whales within 200 miles (322 kilometers) of the
U.S. West Coast to determine which areas were most important to
the whales. An estimated 2,500 of the world's 10,000 blue whales
spend time in the waters off the West Coast of the Americas,
traveling from the Gulf of Alaska all the way down to an area
near the equator known as the Costa Rica Dome.

The ranges of, and distances traveled by, individual whales
varied dramatically. Still, the blue whales consistently returned
to feed in specific locations each year overall — areas with
plenty of tiny shrimplike crustaceans known as krill.

The researchers discovered that busy shipping lanes off Los
Angeles and San Francisco overlap with the two areas of highest
use by tagged blue whales off the U.S. West Coast during the
summer and fall.

However, such a change "is not an easy thing that can be done
quickly," Irvine said. "Shipping companies do not want to do
anything that makes them go farther and use more fuel," he noted.
"Also, in the case of Southern California, the U.S. Navy has
training ranges all around the southern Channel Islands area, and
if the shipping lanes were moved south of where they currently
are, as we suggest, they would go near the training range, so the
Navy would have to be consulted and agreeable to make this
happen."

That being said, "it's in the shipping companies' interest to not
hit whales," Irvine said. "When ships hit whales, the shipping
companies' insurance companies require them to have their ships
inspected for damage before they go across the ocean," Irvine
added. "There are limited facilities to do that, and ships have
to sit for a long time and miss out on income while they get
inspected."

This means protecting the whales "is a win-win for everybody, and
that's always good," Irvine said. "You take whatever reason you
can get."

In the future, the scientists hope to use their data to help
develop models predicting where blue whales might be. "We can use
that data to help make the decision for a seasonal change or
closure of shipping lanes," Irvine said.

The scientists detailed their findings online July 23 in the
journal PLOS ONE.